1. Field of the Invention
The present invention relates to an image processing apparatus that reads an image of a document by moving an image reading unit from a reference position along the document in a predetermined direction for scanning. In addition, the present invention relates to a method for controlling a return speed of the image forming unit at returning to a home position (reference position) after completion of scanning.
2. Description of the Related Art
A scanner, a facsimile, a printer, a copying machine and a composite apparatus (called also an MFD: Multi-Function Device) executing these functions comprise an image reading unit for reading a document as image data. In general, the image reading unit comprises an image sensor such as a CCD (Charge Coupled Device) or a CIS (Contact Image Sensor) and this sensor is arranged just under a contact glass such that the light receiving surface of the image sensor is opposed to the contact glass. In addition, the image reading unit supports the image sensor so as to be capable of reciprocally move along the document placed on the contact glass. Accordingly, the image reading unit obtains image data by receiving driving force of a motor and moving the image sensor along the document for scanning while converting received light to electric data.
In addition, the image sensor is controlled to return a home position, that is, a reference position in which it was positioned before scanning, at a predetermined return speed so as to read the image of the next document placed on the contact glass.
As a scanner control apparatus for controlling the return speed, a prior art disclosed in Japanese Patent Application Laid-Open No. 2001-19656 is well known. According to the scanner control apparatus in the prior art, the return speed is changed according to a moved distance of a scanner (image sensor) in scanning a document. In addition, Japanese Patent Application Laid-Open No. 11-146144 (1999) discloses a scanner drive control apparatus that can reduce an oscillating quantity of an image forming apparatus body by changing accelerated velocity when a scanner returns to its home position according to the moved distance of the scanner such that the oscillating quantity of the image forming apparatus may become minimum.